Modification with mesoporous platinum and poly(pyrrole-3-carboxylic acid)-based copolymer on boron-doped diamond for nonenzymatic sensing of hydrogen peroxide

A sensitive, accurate, free of oxygen interference electrochemical sensing approach was developed in this study for H₂O₂ level, an important parameter in clinical, biological and environmental fields. A boron-doped diamond (BDD) electrode was modified with mesoporous platinum (MPrPt) by electrodeposition of Pt-Cu alloy and anodic dissolution of Cu from the alloy, followed by the electropolymerization of a poly(pyrrole-3-carboxylic acid) (PPy3C) and polypyrrole (PPy) (PPy3C: PPy = 4:1, molar ratio) copolymer. SEM micrographs revealed that MPrPt irregularly spreads on the BDD surface as ~ 100 nm mesoporous and snow-flake-like nanoclusters, with a pore size of 10 ~ 15 nm, and a trace amount of remnant Cu. The resulting Pt roughness factor and the effective surface area of the MPrPt/BDD were significantly larger, and its charge-transfer resistance was much smaller than those of the Pt nanoparticle modified BDD electrode. The PPy3C-PPy/MPrPt/BDD electrode exhibited very much sensitive, selective, precise, accurate, stable, reproducible, and a wide linear range of H₂O₂ responses at neutral pH under ambient condition, with similar sensitivity and S/N ratio to those under nitrogen protection. The limit of detection (LOD) for H₂O₂ was 2 μM, with linearity range of 5 μM ~ 49 mM (4 orders of magnitude). The BDD substrate, MPrPt, and the PPy3C-PPy copolymer together exerted a synergic effect to the prominent sensing performance. The detection was free from endogenous oxygen interference, one of the most critical issues in microanalysis, in vivo monitoring and field applications.